The individual component parts of partial dentures are the saddles, occlusal rests, direct and indirect retainers, and connectors. The saddle is that part of the partial denture which replaces lost alveolar tissue and carries the artificial teeth; they may be designated as free-end or bounded. In the former, an abutment is present only at the mesial (forward) end of the saddle; in the latter, an abutment tooth is present at both ends.
Precision attachments are one type of direct retainer, the principal other one being the clasp. Retainers function to provide positive retention to the denture; and second, to provide bracing for the denture against lateral forces and to transmit these forces to the abutment teeth. They may be more efficient than a clasp but the clinical circumstances in which they are required calls for a careful assessment. Where their use is indicated, the attachments currently used are commercially prefabricated and may be classified into several types. The present invention is directed to an improvement in the intracoronal precision type. Such attachments have two parts - male and female. The female part is in the form of slot that is embedded into some type of restoration, such as a crown or inlay in the abutment tooth. The male portion of the flange that fits into the slot and is attached into the saddle of the denture (see FIG. 9.42 of Osborn et al.). This type of attachment provides rigid connections between the tooth and the saddle and further serves the purposes of a retentive clasp arm, a bracing clasp arm and an occlusal rest, all in one unit. Disadvantages of the present attachments include: a) extensive preparation of the abutment tooth is necessary, and for free-end saddle dentures, a minimum of two teeth on each side of the arch must be prepared and splinted together. The chair side and laboratory preparation times required are substantial together. Together with the cost of the precious metal attachments themselves, this results in an expensive partial denture.